Most liquid fuel systems for internal combustion engines include one or more pumps and valves for delivering pressurized fuel to combustion chambers of the engine. In higher pressure fuel systems, such as those typically referred to as common rail fuel systems, priming the fuel system can be problematic. For instance, after a filter change or other servicing, some air may enter the system. Typically, this air must be evacuated by priming the system prior to starting the engine. Because the system operates at such high pressures, the fuel system may include a bleed line with a bleed orifice that allows trapped vapor to be evacuated back to the tank during a priming operation, rather than requiring the priming strategy to overcome relatively high opening pressures of regulating valves within the fuel system. Thus, a bleed line may help facilitate quicker priming of a fuel system, but such a strategy is not without consequences. For instance, during prolonged periods of engine shut down, vapor from the tank can migrate into the fuel system in a reverse direction along the bleed line. While fuel vapor entering the fuel system in this manner is not a problem, it can be perceived as a problem due to the extra engine cranking time necessary to evacuate the fuel vapor back to tank prior to engine start up. Thus, the fuel system may be working perfectly, but an operator may perceive a problem with engine cranking times on the order of three to ten seconds necessary to evacuate the fuel vapor from the fuel system prior to engine start.
The present disclosure is directed to at least one of the problems set forth above.